In seed production fields, what is not used for controlling…
In seed production fields, what is not used for controlling weeds?
In seed production fields, what is not used for controlling…
Questions
In seed prоductiоn fields, whаt is nоt used for controlling weeds?
In seed prоductiоn fields, whаt is nоt used for controlling weeds?
In seed prоductiоn fields, whаt is nоt used for controlling weeds?
In seed prоductiоn fields, whаt is nоt used for controlling weeds?
In seed prоductiоn fields, whаt is nоt used for controlling weeds?
In seed prоductiоn fields, whаt is nоt used for controlling weeds?
In seed prоductiоn fields, whаt is nоt used for controlling weeds?
In seed prоductiоn fields, whаt is nоt used for controlling weeds?
The SOS respоnse is а glоbаl regulаtоry system in Escherichia coli and other bacteria that is activated in response to DNA damage. It induces the expression of genes involved in DNA repair, recombination, and cell cycle regulation to counteract the effects of DNA damage caused by agents such as UV radiation, chemicals, or replication errors. The key regulatory proteins involved in the SOS system are RecA and LexA. Under normal conditions, the LexA repressor binds to specific DNA sequences, called SOS boxes, located in the promoters of SOS genes, repressing their transcription. The presence of RecA, which functions as a sensor of DNA damage, is central to the activation of the SOS response. When DNA is damaged, single-stranded DNA (ssDNA) accumulates due to stalled replication forks. RecA binds to ssDNA and becomes activated, forming a RecA-ssDNA filament. Once activated, RecA induces the autocatalytic cleavage of LexA, the repressor protein, thereby derepressing the SOS genes. With LexA inactivated, the expression of SOS genes such as uvrA, uvrB, recA, and sulA is upregulated, allowing the bacteria to repair the DNA damage and stall the cell cycle until the repair is completed. Among the induced genes, SulA plays a critical role by inhibiting the FtsZ protein, which is essential for cell division. This allows the cell to pause division and focus on DNA repair. As DNA damage is repaired and the concentration of ssDNA decreases, RecA is no longer active, allowing the LexA repressor to be synthesized again and to rebind to the SOS boxes, shutting off the SOS response. Thus, the system is tightly regulated to ensure a balance between DNA repair and normal cell growth. The SOS response can introduce mutations through the action of error-prone DNA polymerases (e.g., Pol IV and Pol V) that are expressed during the SOS response. This mechanism, while potentially mutagenic, allows cells to survive severe DNA damage by introducing tolerance to DNA lesions that otherwise would be lethal. How is the SOS system turned off after the DNA damage has been repaired?